Reciprocating piston tri-lobed cam engines are disclosed in the following patents:
______________________________________ U.S. patents 1,765,237 1,792,062 2,124,604 4,697,552 ______________________________________
In each of the foregoing patents a pair of diametrically opposed pistons are provided which are coupled together in push-pull relationship by an inextensible link. Each piston has a cam-follower, the link serving to maintain the cam-followers in contact with the cam at all positions of rotation thereof. The coupling together of the pistons in this manner necessitates the shaping of the tri-lobed cam such that the dimension between diametrically opposed portions is substantially constant. Generally speaking, such shaping includes a flattening of the lobes of the cam and the formation of a concavity between adjacent pairs of lobes. These engines have a relatively large angular interval over which they are not self-starting when operated as external combustion engines.
In U.S. Pat. No. 1,203,855 there is disclosed a tri-lobed cam engine wherein the pistons are not connected together, whereby they are freefloating. The cam of this engine is asymmetrically shaped, whereby the engine would be suited for operation in one direction only. Moreover, the interaction between the cam-followers and the cam would generate a severe reactive force which urges the piston into contact with the wall of the cylinder in which it reciprocates, promoting a rapid wear.
It is an object of this invention to provide improved tri-lobed cam engines.
It is another object of this invention to provide tri-lobed cam engines which utilize free-floating pistons wherein inter-reactive forces between the piston and cylinder wall are reduced.
It is still another object of this invention to provide tri-lobed cam engines which have a symmetry whereby they may be operated in either forward or reverse directions with no change in either power or torque.
It is yet another object of this invention to provide tri-lobed cam engines that have a simple modular construction whereby the number and size of the cylinders can be easily altered.
It is a further object of this invention to provide tri-lobed cam engines that may be self-starting when operated as external combustion motors.